Hi!

I have finally managed to cross 600bhp with my car (MY10 XKR). It required both lower and upper supercharger pulleys replacement. But... Before the lower pulley it was increasing the power till the very end. Now - it dies at 5000-5200 rpms.

I'm wondering about the root cause. First hypothesis- wastegate releasing additional boost. Are these 600+ bhp builds do any changes to the wastegate? Probably it is easier with newer models as they have an electronic one. Here - it is the older version...

Any thoughts?

Upper pulley:



upper and lower pulleys:

 

Not that you ever would, but that flat torque curve would make this a tow rig that could shame a diesel.

 

The AJ133 SC is renowned for it's flat torque curve.
From memory a stock engine from the factory is quoted as making max torque from 2,000 to 4,500 rpm.

 

valve float?

 

interesting input- need to think about it. Car has equal compression on each cylinder, but not sure if it matters in this case.

 

your car is capable to push over 700hp on upper pulley only. The ecu tune is what's holding it back that's why it made less power after the crank pulley because now u making more power alot sooner and all the torque limiters kick in. Nobody has been able to remove this limiters sadly

 

Fuel pump can't keep up? Fuel filter clogged? Whole fuel delivery system built to support less HP?

 

rather it's not the case - we were able to add more fuel, but it didn't make any difference.

 

What tuner are you using?
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.
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i'm in Poland - local company (you have a name on the dyno chart).

 

Don't you need to reprogram/tune the ECU so it could recognize the new power your car putting out?

 

well, yes it is obviously done (without it it would be actually below OEM power as it would be highly "overfueled").

 

Idk how else to help cause all I know is once you do something to a car to upgrade the horsepower, everything else including the transmission gotta be tuned to recognize the new modification from what I was told by a mechanic that know how to do serious mods on cars that build hot rods and things

 

This is the info I got back from a well know tuning company when I enquired about doing both pulleys:

"The only issue I’ve ever run into is if both upper SC and lower Crank are installed on a Denso equipped vehicle, a lot of playing around with the file needs to be done or else the excessive boost is vented off. For the time being, we’ve gone the route of NOT recommending both pulleys on a Denso equipped vehicle. But in your case with just the upper pulley, shouldn’t be any issue providing it’s tuned “correctly”."

The later cars e.g. F Type, have electronically controlled supercharger boost valves so can be tuned better. The Denso ones are mechanical.

There is a lot of information in this post about supercharger pulley sizes and combinations:

https://www.jaguarforums.com/forum/f...1/#post2136732

 

Here's Denso dual pulley setup, right before a trans remap (trans was limiting torque).
However now i can make same numbers with a stock pulleys (benefits in avoiding a traction problems).

Same day, same hour, same dyno, stock tune in a PCM.

 

When you look at my dyno chart - what is your hypothesis? Purely software issue?

 

Either a softare or a bypass plate wear.

 

Pardon my ignorance- by bypass plate you are referring to the actuator (C2D9331) or other part? I'd be grateful!

Thanks

 

It's a throttle plate inside a supercharger, driven by bypass actuator.

 

Is there any way to test it without taking off and disassembling the whole supercharger?